Editing Stream gradient (section)

==Fluvial erosion==
A stream that flows upon a uniformly [[erosion|erodible]] substrate will tend to have a steep gradient near its source, and a low gradient nearing zero as it reaches its [[base level]]. Of course, a uniform substrate would be rare in nature; hard layers of [[rock (geology)|rock]] along the way may establish a temporary base level, followed by a high gradient, or even a [[waterfall]], as softer materials are encountered below the hard layer.

Human [[dam]]s, [[glaciation]], changes in [[sea level]], and many other factors can also change the "normal" or ''natural'' gradient pattern.